High intensity vehicle lamp with shield preventing unwanted reflection

ABSTRACT

A lamp, for a road vehicle, of the kind including a reflector supporting a quartz iodine or equivalent high intensity bulb, and having a first light shield positioned with respect to the bulb so as to prevent light issuing from the lamp without first being reflected from the reflector, further includes a second light shield. The second light shield is positioned with respect to the bulb so as to prevent those light rays which have been refracted by the deformed portion of the envelope of the bulb, at the base of the bulb, and which would be reflected by the reflector so as to issue from the lamp upwardly relative to the axis of the reflector in use, from striking the reflector.

United States Patent [72] Inventor Harris Vernon Hicks [56] References Cited Lichfl ngland UNITED STATES PATENTS P 750,165 1,250,030 12/1917 Schickerling 313/1 13x ggff fi 3 1,772,175 8/1930 Arbuckle 240/412;

826,7l0 3 1958 L' b 313/11 731 Assignee Joseph Lucas (Industries) Limited Bi i h E l d Primary Examiner-James W. Lawrence [32] Priority Aug. 16, 1967 Assistant ExaminerDavid OReilly [33] n Britain Attorney-Holman & Stern [3 l No. 37696/67 ABSTRACT: A lamp, for a road vehicle, of the kind including [54] SHIELD a reflector supporting a quartz iodine or equivalent high inten- 2 claims 5 Drum as sity bulb, and having a first light shield positioned with respect a to the bulb so as to prevent light issuing from the lamp without [52] U.S. Cl. 313/113, first being reflected from the reflector, further includes a 240/4135, 240/4l.4, 313/117 second light shield. The second light shield is positioned with [51 Int. Cl. F2lv 7/00, respect to the bulb so as to prevent those light rays which have H0 1 j 5/02 been refracted by the deformed portion of the envelope of the [50] Field of Search 240/4l.3 5D bulb, at the base of the bulb, and which would be reflected by 46.19, 46.49, 46.53, 46.55, 41.25; the reflector so as to issue from the lamp upwardly relative to 313/1 13-1 17 the axis of the reflector in use, from striking the reflector.

l 1 1 4 1 Z 4? E I fig 47 46 4 59} V a4 y fi fl 4 47 z 1/ 2 PATEINTEUJANSIQII I I 3.553.519

' snzulnrz HARRISVERN N HI CKS HIGH INTENSITY VEHICLE LAMP WITH SHIELD PREVENTING UNWANTED REFLECTION This invention relates to lamps, for. road vehicles, of the kind including a reflector, a quartz iodine or equivalent high intensity bulb carried by the reflector, and a first light shield positioned with respect to the bulb so as to prevent light issuing from the lamp without first being reflectedby the reflec- 101.

According to the invention'a lamp of the kind specified further includes a second light shield positioned with respect to the bulb so as to prevent those light rays which have been refracted by the deformed portion of the envelope of the bulb at the base of the bulb, and which would be reflected by the reflector so as toissue from the lamp upwardly relative to the axis of the reflector inuse from striking the reflector.

One example of the invention is illustrated in the accompanying drawings wherein:

FIG. 1 is a sectional view of a sealed beam lamp for a road vehicle,

FIG. 2 is a sectional view on the line 2-2 in FIG. I,

FIG. 3 is a perspective view of the quartziodine bulb shown in FIG. 1,

FIG. 4 is a perspective view of a light shield shown in FIG. 1 and f t FIG. 5 is a perspective view of the ceramic bulb support shown in FIG. 1, it being appreciated that FIGS. 1'to 5-are not all drawn to the same scale.

Referring to the drawings, the lamp includes an outer casing 11 adapted-at 12 to be secured to a road vehicle. Secured within the casing 11, by means of a clamping ring'13, is a sealed beam lamp unit 14, including a paraboloidal reflector 15 and an integral lens 16, the sealed enclosure defined by the lens 16' and the reflector 15 being filled with an inert atmosphere. ThereflectorlS is mouldedjin glass and secured to the outer surface thereof is a pair of conductive blade terminals 17, 18. Extending through sealed pinches 19, 21 in the reflector 15, adjacent the terminals 17, 18 is a pair of stiff conductive leads 22, 23 electrically connected respectively to the terminals 17, 18. The production of the pinches 19, 21 results in local distortion of the inner surface of the reflector adjacent the pinches and when the inner surface of the reflector is aluminized to render it highly reflective the area of the inner surface of the reflector 15 adjacent the pinches 19, 21 is masked so that the distorted areas of the reflector are not aluminized. Thus the amount of light which will be scattered by the distorted areas of the reflector 15 is minimized.

The leads 22, 23 extend forwardly from the reflector, for a short distance, parallel with the axis of the reflector and are then bent through 90 to extend towards one another for a further short distance.

\ Extending parallel with the axis of the reflector are a further pair of conductive leads 24, 25 which are welded at one end to the free ends of the leads 22, 23 respectively. The leads 24, 25 extend through corresponding parallel bores 27 in a ceramic bulb support member 26. The member 26 comprises a rectangular block 28 of ceramic material having a pair of parallel fingers 29 integral therewith and extending from one end thereof. The end of the block 28 remote from the fingers 29 is formed with a transverse groove 31 in which the bent portions of the leads 22, 23 lie. The bores 27 extend from the base of the groove 31 and terminate between the fingers 29.

Engaged with the member 26 is a quartz iodine bulb 32. The bulb 32 comprises a generally cylindrical quartz envelope 33 housing a tungsten filament 34. The base of the bulb 32 is formed by a pinch 35 and enclosed in thickened edges 36 of the pinch 35 area pair of conductive ribbons 37, 38 which at one end are interconnected by the filament 34 and which at their other ends are connected to the leads 24, 25 respectively so that an electrical circuit between the terminals 17, I8 is completed through the filament 34. Between the edges 36 of the base of the bulb is an integral web 39 and the bulb 32 is engaged with the member 26 by inserting the web 39 between the fingers 29 of the member 26 until the free end of the web 39 engages the block 28 of the member 26, the member 26 serving to minimize flexure of the leads 22, 23, 24, 25 in use and thereby to minimize movement of the bulb relative to the reflector. I

Trapped between the base of the: bulb 32 and the member 26 is a rear light shield 41 which includes a pair of side portions 42 which extend parallel with the axis of the reflector l5 and which masks the edges 36 of the pinch 35 and the deformed parts of the envelope 33 adjacent the edges 36, and a top portion 43. The portion 43 includes a part 430 which ex tends at right angles to the axis of the reflector l5 and integral with the part 43a is a further part 43b which extends parallel with the axis of the reflector. The portion 43 masks the deformed part of the envelope 33 adjacent the web 39 which is uppermost in use.

Extending parallel with the leads 22, 23 from a third pinch 44 in the reflector 15 is a rigid rod 45 which at its end remote from the reflector 15 carries a front light shield 46. The shield 46 is in the form of a cup-shaped member which encloses the forward end of the envelope 33. The shield 46 includes a resilient metal strip 47 which engages the envelope 33 at a pair of spaced points and the shield 46 itself engages the envelope at a third point which is the lower most point of the envelope 33 in use, so that the envelope is held against movements in directions transverse to the axis of the reflector 15 by the shield 46 and the rod 45, in addition to member 26. The manufacture of the envelope 33 involves the formation of a pinch 33a at the end of the envelope. 33 remote from the reflector 15, the pinch 33a being enclosed within the shield 46. The edge of the shield 46 lies on the surface of a cone having its apex at the center of the filament 34 and its base at the front edge of the reflector so that any light from the filament 34 which is travelling in a directionsuch that it would pass directly through the lens 16, without first being reflected from the reflector 15 is blocked by the shield 46.

In usewhen the lamp is assembled the leads 24, 25 are welded to the ribbons 37, 38 of the bulb 32 and the rear shield 41 is engaged with the base of the bulb 32, a pair of tags 42a integral with the side portions 42. of the shield 41 being deformed to grip the web 39 of the bulb 32. The bulb 32 and shield 41 are then engaged between the fingers 29 of the member 26 with the leads 24, 25 extending through the bores 27 of the member 26 into the groove 31. The ends of the leads 24, 25 are then welded to the ends of the leads 22, 23 respectively so that the bent portion leads 22, 23 lie in the groove 31. The shield 46 is then engaged with the envelope 33 of the bulb 32 and is moved to its correct position, a tag 47a integral with the strip 47 of the shield 41 being welded to the rod 45 to support the bulb 32 firmly in position relative to the reflector 15.

It is important when using a high intensity lamp that light from the lamp is directed down onto the road and that a minimal amount of light is scattered upwardly from the lamp. It will be appreciated that the pinch 33a, if it were not masked by the shield 41, would scatter light from the filament 34 in all directions. Moreover the deformed areas of the envelope 33 around the pinch 35, and the pinch 35 itself, refract the light from the filament and so constitute light sources themselves. The additional light sources constituted by the pinch 35 and its surrounding part of the envelope 35 are behind the focal point of the reflector 15 and so would produce a divergent beam issuing from the lamp. However the side portions 42 and the top portion 43 of the rear shield 41 block all of the light which would produce such a divergent beam with exception of that part of the light issuing from the lower most part of the envelope 33 which would result in a divergent beam directed downwardly onto the road. Furthermore, the portion 43 of the shield 41 is also positioned to block any light which would be reflected from the deformed area of the reflector 15 around the pinch 44, since the area around the pinch 44 unlike the areas around the similar pinches 19, 21- is aluminized when the reflector is manufactured and so is highly reflective. The area around the pinch 44 is not masked with the areas around the pinches 19, 21 during the aluminizing process, since it has been found more convenient to utilize the shield 41 to prevent reflection from the area around the pinch 44.

ln conventional lamps employing quartz iodine or equivalent high intensity bulbs, unless great care is taken in design to avoid excessively high temperatures near the pinch 35 there is a possibility of early failure of the bulb because of gradual oxidation of the ribbons 37, 38. This oxidation causes the ribbons 37, 38 to swell and the swelling eventually cracks the pinch 35, allowing air to enter the bulb, whereupon the bulb burns out. Since the bulb 32 of the present construction is housed in an enclosure containing an inert atmosphere, the ribbons 38, 39 cannot oxidize, so this hazard does not arise.

It will be appreciated that the light shield 46,and in particular the light shield 41, are so constructed that they do not scatter the light which they are intended to block in directions which would have deleterious effects on the accurate high intensity beam issuing from the lamp.

I claim:

VI. A lamp for a road vehicle, comprising in combination a reflector, a lens defining with said reflector an enclosure, a pair of terminals at the exterior of said enclosure, a pair of leads extending from said terminals through the reflector into said enclosure, a high intensity quartz halogen bulb having an envelope and a filament within said envelope, the ends of said filament extending through a sealed, deformed portion of said envelope to a position external of said envelope, support means fixedly mounting said bulb in said enclosure, means connecting said lead to said ends of the filament to complete a circuit from said terminal to the filament, a first light shield, means mounting said first light shield within said enclosure to prevent light from the bulb issuing from the lamp without first striking the reflector, a second light shield, and means mounting said second light shield between said deformed portion of said envelope and the reflector to prevent light refracted by said deformed portion of the envelope striking the reflector and then issuing from the lamp upwardly relative to the axis of the reflector. v

2. A lamp as claimed in claim 1 wherein said lens and said reflector define a sealed enclosure which contains an inert atmosphere. 

1. A lamp for a road vehicle, comprising in combination a reflector, a lens defining with said reflector an enclosure, a pair of terminals at the exterior of said enclosure, a pair of leads extending from said terminals through the reflector into said enclosure, a high intensity quartz halogen bulb having an envelope and a filament within said envelope, the ends of said filament extending through a sealed, deformed portion of said envelope to a position external of said envelope, support means fixedly mounting said bulb in said enclosure, means connecting said lead to said ends of the filament to complete a circuit from said terminal to the filament, a first light shield, means mounting said first light shield within said enclosure to prevent light from the bulb issuing from the lamp without first striking the reflector, a second light shield, and means mounting said second light shield between said deformed portion of said envelope and the reflector to prevent light refracted by said deformed portion of the envelope striking the reflector and then issuing from the lamp upwardly relative to the axis of the reflector.
 2. A lamp as claimed in claim 1 wherein said lens and said reflector defiNe a sealed enclosure which contains an inert atmosphere. 